444 marlin and 400 gn bullets

R

Ruga Booga

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Does anybody know where I can get some 444 reloading data for these lead bullets? They are 417 grains and sized to .433. I will be shooting them out of a Thompson Center Encore with a 22-inch MGM barrel. The other bullets are for comparison. L to R- Hornady 300 xtp, Hornady 265 fp interlock and Speer 240 jhp. Does anybody else have a similar setup? If so what kind of accuracy are you getting? I am expecting this rifle to perform sub moa. The only powders I have for the 444 are Trail Boss and h335. Only reference I have is 2015 hodgdon manual. Powder recommendations welcome. Also, what do you think the best book is for reloading straightwall cartridges?Thanks in advance
 

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444

Go to Beartooth Bullets. There is a series of articles about the .444, the third article deals with reloading with heavy bullets. The heaviest mentioned is 405 grains. There is no data for H335.
Get some Reloader 7 or Varget.

https://www.beartoothbullets.com/tech_notes/archive_tech_notes.htm/28

That was all I was able to find near to your bullet weight. Even the data at the Marlin Owners forum goes only to 365 grs.
There is some info at Kelly’s Leverguns for 400 grainers using RL7 or Varget (which seem to be the propellants of choice for heavy bullets in .444)
 
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The go-to powder for .444 Marlin is, well, two powders: H4198 and IMR4198.

However, Reloder 7 edges out the 4198s with heavy bullets. (Not Accurate #7!!)

The best discussions that I've seen on load data for 444 heavies were all over in the 444 forum at MarlinOwners. There, mt_sourdough, Flat_Top, myself, and a couple other guys discussed quite a few things that we've run, as well as what we considered a safe starting point for most 380+ gr bullets seated to a reasonable COAL.
One thread that comes to mind, specifically, was a discussion about mt_sourdough's multiple iterations of his "Razberry" bullet (ranging from 405 gr to 435 gr).

I didn't check that BTB article, so I don't know if it was mentioned. But you need to be careful with seating depth for heavy bullets, as seating too deeply will bulge the case and preclude chambering. (Hence the lack of common usage of heavy bullets in .444 Marlin, since lever guns and standard throats don't allow long COALs, but the case geometry doesn't really allow deep-seating.)

I would offer some of my load data as a very basic starting point, but all I have now is for my 437 gr bore-rider bullet which runs a ridiculous 3.250" COAL, allowing for more case capacity than anything else in the class. (Single-shot only. And it was a custom mold.)
 
twist rate

I am curious as to the twist rate in the bolt rifle/MGM barrel mentioned, as opposed to the factory Marlin lever rifle twist rate?
 
I am curious as to the twist rate in the bolt rifle/MGM barrel mentioned, as opposed to the factory Marlin lever rifle twist rate?
Click to expand...
MGMs use a 1:20" twist rate.
Marlin used a 1:38" twist rate for Micro-Groove barrels ('63-'98), and a 1:20" twist rate for barrels with "Ballard" rifling ('98+). H&R also used the 1:20" twist.
Other manufacturers, such as Winchester, CVA, etc. usually used something in between (1:24", 1:26", 1:28", 1:30", or 1:36").

The 1:20" twist rate, in my opinion, is overkill for almost any 'reasonable' .444 Marlin bullet weight. ...But it does mean that rather heavy bullets (400-500 gr) can be fired at velocities as low as 1,200 fps while remaining stable.
 
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That article at Beartooth is a huge amount of useful information. I decided to pick some Reloder7 up at my local Cabelas to work up a load with these bullets. Since there is no load testing for my specific bullet, i am using the data from Beartooth for their 405gn lbt wlngc sized .432 over 37 gns of Rel-7. The bullets i am loading are 417 gn lbt wlngc sized .433. I reloaded 10 cartridges, 5 with 36 gns of Rel-7 and 5 with 37 gns. I did not reduce the load much because Beartooth said they were nowhere near max levels. OAL is 2.71. Any shorter and the bulge from the bottom of the bullet would not let it chamber. Its hard to see in the picture but the bullet actually engages the rifling which from what i heard is great for accuracy. I have not fired these loads and i am in no way recommending this load data to be used by anyone. I am posting in order get your thoughts and/or concerns about this load in my Thompson center encore pro hunter with Mgm 22in. barrel.
 

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Just going on gut instinct here...
But that seems reasonable to start.

I know I went WAY hotter in a single-shot with a test bullet of similar weight, but not seated quite as deeply.
If you dig deep enough, you'll find data on the internet (not trustworthy, but it's there!) showing 405 gr to 420 gr bullets sitting on charges as heavy as 48 gr. Some are certainly over SAAMI MAP. But, some firearms can handle much more pressure than the SAAMI spec adopted for use in a modified Marlin 336...
 
Thanks Frankenmauser. BTW i finally went and registered at Marlin owners and it is a fantastic website. Definitely more of what i am interested in, mainly big bores.
 
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